Filter cloth



Jan. 13, 1931. C H, M 1,788,657

FILTER CLOTH Filed Nov. 22, 1926 Patented Jan. 13, 1931 CORNELIS HENRI CAALS,OF THE HAGUE, NETHERLANDS FILTER CLOTH Application filed November 22, 1926, Serial No. 150,156, and in the IhTetherlamis Apri1.26, 1926.

The invention relates to improved filterclot-hs for use more particularly in filterpresses and to the improved filter-cloths produced according to this process.

Filter-cloths as at present. used in filterpresses cannot be distinguished from ordinary textile fabrics.

When the filter-press is in operation and the plates are pressed together, the filter locloths frequently wear out very quickly at those places where the plates meet, i. e. at the edges of the filter-plates. The worn out places cause the press to spout or leak and or this reason the filter-cloths have to be constantly under control and frequently mended.

It is the object of the present invention,

to rovide filter-cloths in which these drawbac s are eliminated and therefore the filtercloths according to the invention are characterized by the feature that, they have specially woven strengthening bands at those places, which correspond to the protruding edges of the filter-plates.

Figure 1 shows a filter cloth having heavy warp and weft threads woven into the material at the points to be reinforced.

Figure 2 is amodified'form illustrating a similar arrangement.

Figure 3 shows a filter cloth having a greater number of warp and weft threads at the points to be reinforced.

In the drawing, 'Fig. 1 shows the warp threads a a and weft threads I) b in which the warp and weft threads 0. and b are heavier threads than the warp and weft threads a b. This gives zones of different strength in the cloth and a heavier strength at the border ders are deslred.

so that if out on the lines 1-1 each piece will be reinforced at all its edges.

Figs. 2 and 3 show at d ande zones at which the warp and weft threads are spacedcloser together than at the zone 7. This gives the desired reinforced edges where the cloth is cut on the line 1--1.

Fig. 2 is an enlarged view of Fig. 3 showing at 9 where the warp threads are uppermost.

The strengthening bands are woven into the cloth by either warping and weaving stronger threads or yarns at the desired places or by increasing the number of warps and wefts at those places.

Although the corner-squaresof the filtercloths are of double thickness as compared with the side parts, it has been ascertained that such difference in thickness doesnot cause any leakage and that the plates, when using the filter-cloths according to the invention, closeup as narrbwly as they would do when using any ordinary filter cloth and even better because of the elastic tendency of the plates to bend out somewhat at the corners.

Another adv antage of a filter-cloth according to the invention is that the central part may be woven independently from the o5 side-parts for example of a somewhat finer yarn number than would be possible with ordinary filter-cloth which needs must possess a definte minimal strength in the centre as well as at the sides. This involves a quicker filtering of the material through the filter-cloths prepared according to the invention. In fact the centre of the filter- Gloth according to the invention may be woven from a yarn which is quite different 7 from 'thatwhich is used for the side parts and consequently yarns .may be selected which will 've the desired properties, viz, strength anft luick filtering.

If for special purposes very strong yarns or threads are woven into the borders, the plates or frames of the filter press may, if desired, be fraised' out or rooved at the corners of these lates or rames may be provided with rub er parts which fit between the corner-squares of the filter cloth. This measure is only taken when extra strong border so that a double filter-cloth with all round strengthened borders and 'a=:dhuble strengthened border in the middle, to-overlap 1 the top of .theframes oi" the filter+press, is obtained.'. I

Having now particularly described and ascertained the nature of my said invention and in what manner-the same is to be performed, I declare that what I claim is:

Aefilter cloth adapted to be used between the frames of filter presses consisting of two central'woven filtering portions and a circumamb ient strengthened woven marginal portion in the shape of a rectilinear figure 8,

the central filtering portions being within the marginal portions and being separated by the intermedlate transverse portion of said figure 8. I

In testimony whereof I- afiix my signature.

CORNELIS HENRI GAALS. 

